Citation Markup Assistant assigning incorrect links to publications

Hello - I’m just starting to work with the Citation Markup Assistant in OJS 2.4.2, and am noticing that it is consistently assigning incorrect URLs for citations. Multiple articles are getting URLs assigned to them that seem to be encyclopedia entries from the NLM TOXNET database for the first element named in the article title. (In the example below, the URL is for the “Cadmium, elemental” entry in TOXNET. The PMID is correct, though.) I tried turning off PMC as a citation service (so it’s just checking against CrossRef now), in case that was somehow causing the problem, but it didn’t fix it. Any ideas on why this is happening? What is being searched to produce these results? Thanks!